1. Field of the Invention
The present general inventive concept relates to a hard disk drive apparatus, a method to compensate repeatable run out of a hard disk drive apparatus, and a computer-readable recording media recording the method, and more particularly, to a hard disk drive apparatus which can adaptively operate an RRO compensator according to a seeking path of a magnetic head and accordingly improve the servo control and track mis-registration (TMR) performances, a method to compensate RRO of a hard disk drive apparatus, and a computer-readable recording media recording the method.
2. Description of the Related Art
Hard disk drive apparatuses (HDDs) are one of memory devices formed of electronic parts and mechanical parts and recording and reproducing data by converting digital electric pulses to a magnetic field that is more permanent. The HDDs are widely used as auxiliary memory devices of computer systems because of fast access time for a large amount of data.
With the recent development in the technology related to the head, the storage density of an HDD has been sharply increased. Accordingly, it becomes more important to maintain a track mis-registration (TMR) performance over an appropriate level without losing stability in recording and reproducing performance of the head.
Repeatable run out (RRO) and non-repeatable run out (NRRO) are factors that affect the TMR performance. Among them, RRO is mainly generated due to the eccentricity of tracks with respect to the center of a disk or the deformation of a disk. RRO works as a disturbance in servo control to deteriorate the servo control performance of a head. RRO can be divided into RRO components having various frequencies such as 1x, 2x, 3x, . . . , Nx. Here, the unit “x” signifies a frequency corresponding to the rotational speed of a disk.
Of the RRO components, the 1x, 2x, and 3x RRO components are generated mainly due to the eccentricity of tracks with respect to the disk center and exist throughout the overall area of the disk. The RRO components over 4x are generated mainly due to the disk deformation and tend to greatly decrease from the inner diameter (ID) area of a disk to the outer diameter (OD) area.
To compensate RRO, an RRO compensator and a RRO correction code (RCC) are used. In general, the RRO components under a predetermined frequency are compensated using the RRO compensator while the RRO components over the predetermined frequency are compensated using the RRO correction code. For example, 1x through 6x RRO components are compensated using the RRO compensator and 7x or higher RRO components are compensated using the RRO correction code. The RRO compensators are provided in parallel in a number corresponding to the number of RRO components to be compensated.
However, when the conventional RRO compensator is used, a plurality of RRO compensators provided corresponding to the RRO components under a predetermined frequency are all turned on regardless of a seeking path of a magnetic head. Accordingly, the 4x or higher RRO components that are greatly decreased in the OD area of the disk are compensated by the RRO compensator without discrimination. As a result, when the magnetic head located in the ID area is set to seek data in a middle diameter (MD) area or the OD area and data recording or reproducing is performed, over-compensation is made to the 4x or higher RRO components by the RRO compensator. Thus, seek time increases and a position error signal (PES) increases.